General description Digital display with power supply, detachable design, and anti-reverse connection protection. This battery case can charge up to 21 flat head 18650 batteries and can function as a power bank when the built-in battery is used. The normal version requires a charging cable, while the cable-free version allows for quick charging. Ideal for those with larger charging needs, it features three types of charging interfaces: Micro, USB, and Type-C. The power display lets you monitor remaining power easily, and it comes with a lanyard for convenient portability. Technical specifications Model: T21 Series with Light Battery type: 18650 x 21 flat head battery (solderless) Size: Thickness 62mm, Width 84mm, Length 170mm Inner dimensions (without spring): Thickness 55mm, Width 74mm, Length 129mm Output/Input Maximum Power: 5V-3A, 9V-2A, 12V-1.5A Precautions The battery cannot be used if its outer skin is damaged. Only flat batteries can be used; pointed batteries are not